You're referring to the bosses at the Erebus, and that one of them should have a Second Chance Chest, correct?

You'd have to take that up to Ratbeard, but here's his survey before they can consider to add a Second Chance Chest there.

1. Is the boss in question at the end of a long instance?

2. Does the boss in question have unique loot?

I'm sure you can answer these questions for him.

Yes I am referring to Fin Dorsal's chest

1. No he isn't but it is harder to farm due to lack of sigil2. Yes he does. He drops the cutthroat eyepatch (very rare and is unique to this fight) and the level 10+ version of Fin's Cutters (Which give repel boarders unlike all the other ones and is very rare as well)